A variety of body lumens are subject to undesired strictures or narrowing. For example, blood vessels can be blocked or narrowed by atherosclerosis, while esophageal strictures can arise from individual anatomical differences, or from diseases such as connective tissue disorders. Procedures for dilating or enlarging such strictures or narrowed regions often entail the use of a stent. The stent may be positioned across a particular stricture or narrowed region, and may then be expanded in order to widen the lumen without causing trauma to the wall of the lumen.
Unfortunately, the current stent designs may have a number of drawbacks. For instance, many types of stents cannot be retrieved once they have been deployed. This can be problematic, especially when the stent is no longer needed or when it malfunctions. Another shortcoming associated with many stent designs is that they undergo endothelialization, wherein the tissue of the dilated body lumen grows into the stent. Thus, even when a retrievable stent has been employed, it may not be possible to remove the stent without damaging the body lumen. Finally, many of the current stent designs cannot be compressed sufficiently for endoscope delivery (since the diameter of an endoscope delivery channel is somewhere around 4 mm).
An ideal stent would be highly compressible and thus amenable to endoscope delivery techniques, would be retrievable and may also discourage endothialization.